require 'delegate'

module PropertySets
  module ActiveRecordExtension

    module ClassMethods
      def property_set(association, &block)
        raise "Invalid association name, letters only" unless association.to_s =~ /[a-z]+/
        property_class = PropertySets.ensure_property_set_class(association, self)
        property_class.instance_eval(&block)

        has_many association, :class_name => property_class.name, :dependent => :destroy do

          # Accepts a name value pair hash { :name => 'value', :pairs => true } and builds a property for each key
          def set(property_pairs, with_protection = false)
            property_pairs.keys.each do |name|
              record = lookup(name)
              if with_protection && record.protected?
                logger.warn("Someone tried to update the protected #{name} property to #{property_pairs[name]}")
              else
                send("#{name}=", property_pairs[name])
              end
            end
          end

          property_class.keys.each do |key|
            raise "Invalid property key #{key}" if self.respond_to?(key)

            # Reports the coerced truth value of the property
            define_method "#{key}?" do
              lookup(key).true?
            end

            # Returns the value of the property
            define_method "#{key}" do
              lookup(key).value
            end

            define_method "protected?" do |arg|
              lookup(arg).protected?
            end

            # Assigns a new value to the property
            define_method "#{key}=" do |value|
              instance = lookup(key)
              instance.value = value
              @owner.send(association) << instance
              value
            end

            # The finder method which returns the property if present, otherwise a new instance with defaults
            define_method "lookup" do |arg|
              instance   = detect { |property| property.name.to_sym == arg }
              instance ||= property_class.new(:name => arg.to_s, :value => property_class.default(arg))
            end
          end
        end
      end
    end

    module InstanceMethods
      def update_attributes_with_property_sets(attributes)
        update_property_set_attributes(attributes)
        update_attributes_without_property_sets(attributes)
      end

      def update_attributes_with_property_sets!(attributes)
        update_property_set_attributes(attributes)
        update_attributes_without_property_sets!(attributes)
      end

      def update_property_set_attributes(attributes)
        if attributes && property_sets = attributes.delete(:property_sets)
          property_sets.each do |property_set, property_set_attributes|
            send(property_set).set(property_set_attributes, true)
          end
        end
      end
    end
  end
end

ActiveRecord::Base.class_eval do
  include PropertySets::ActiveRecordExtension::InstanceMethods
  extend  PropertySets::ActiveRecordExtension::ClassMethods

  alias_method_chain :update_attributes, :property_sets
  alias_method_chain :update_attributes!, :property_sets
end